This invention relates to a blood staining system, and more particularly, to an effective, stable Giemsa stain suitable for use in automated blood slide staining devices. Romanowsky-type stains, e.g. Wright's solution and Giemsa's solution, comprise methylene blue and an eosin dye, normally in methanol solution, along with other allied dyes. Typical allied dyes include Azure A, Azure B and Azure C. While these stains are basically similar, Wright's solution differs from Giemsa solution in three respects:
a. Stain preparation--Wright stain solution is prepared with Wright stain powder (a mixture of eosin Y, methylene blue and azures) and methanol whereas Giemsa stain solution is prepared with Giemsa stain powder (a mixture of eosin Y, methylene blue and azures) and a mixture of methanol and glycerol.
b. Staining procedure--for Wright stain the specimens are fixed in methanol and then stained in a mixture of Wright stain solution and 3 to 5 parts of buffer; for Giemsa stain the specimens are fixed in methanol and then stained in a mixture of Giemsa stain solution and 20 to 50 parts of buffer.
c. Stain characteristics--a Giemsa stain gives more intense nuclear staining on all neutrophils than Wright stain. There is more distinct granulation in the neutrophil cytoplasm than is observed with the Wright stain because of the light overall cytoplasm staining. In addition, red blood cells appear more bluish when stained with a Giemsa stain rather than a Wright stain.
The original Giemsa stain which is described by Lillie in Histopathologic Technique and Practical Histochemistry, 3rd edition, McGraw-Hill, New York (1965), pages 584-589, was prepared with Giemsa powder (comprising eosin Y, methylene blue and azures) in glycerol. The procedure called for fixing the blood smear preparation with methanol and then staining it with a dilution of the Giemsa stain in buffer (the procedure called for dilution of 20 to 50 times with the buffer). This original procedure cannot be used with present day automated staining devices, such as those marketed under the Trademark Hema-Tek, because of the presence of glycerol which is not compatable with the stainer due to its high viscosity, the high dilution required and the long stain time.
The present invention involves a 2 component Giemsa stain which is well-suited for use in automated staining devices and a method of staining blood slides using this stain.